WASHINGTON - US Defense Secretary Mark Esper has started keeping himself and his staff physically separated from his deputy's team as one of the precautions to prevent the spread of the coronavirus from impacting the Pentagon's operations.

"We are attempting to put ... a bubble around the two of them," Pentagon spokesman Jonathan Hoffman told a news briefing, adding Esper's visitors were being limited and screened.

Hoffman said a total of 18 servicemembers have tested positive so far, up from 10 on Saturday and just four a week ago.

He and another official acknowledged the US military's ability to build tent hospitals to help civilian authorities in the United States grapple with a potential influx of coronavirus patients but suggested no such request had come so far.

Reuters